Conventionally, the household dehumidifier uses a refrigerant compressor to condense the moisture in the air to achieve dehumidification. However, the use of refrigerant results in problems such as ozone layer depletion. Therefore, there is need in developing a novel dehumidification technique without using refrigerant.
Among all the dehumidifying technologies available today, there is a membrane dehumidification device, which requires neither the heater nor the refrigerant. The membrane dehumidification device is able to remove moisture from indoor air through a water vapor-air separation membrane and a vacuum pump. Since the dehumidifying mechanism in the membrane dehumidification device is achieved through the use of a water vapor selective membrane, not only the dehumidification is not restricted by ambient air temperature and moisture content, but also does not need to use any refrigerant as those conventional dehumidification devices did.
The performance of the membrane dehumidification device depends on the characteristic of the water vapor selective membrane. Therefore, a novel membrane with a high water vapor permeance and high water/air separation factor is desired for improving the performance of the membrane dehumidification device.